Great Lakes contaminant source: Your driveway
They’re one of the most widespread and potentially toxic contaminants in Great Lakes tributaries: polycyclic aromatic hydrocarbons, or PAHs. They pose a greater risk to aquatic creatures than even herbicide and insecticide pollution.
A new study looked for PAHs in the sediments of 71 Great Lakes tributaries across six states, then used multiple methods to determine the source. The study points to a particular leading culprit: pavement dust from coal-tar sealed driveways and parking lots.
“Parking lots had a much stronger relationship with PAH concentrations than there was with roads – and parking lots and roads are pretty similar,” said Austin Baldwin, a hydrologist with the U.S. Geological Survey and co-author of the study. “A big difference between them is parking lots often get sealed with coal tar-based or asphalt-based sealant, and roads don’t.”
The USGS study took sediment samples from 71 tributaries to the Great Lakes in Michigan, Wisconsin, Minnesota, Indiana, Ohio and New York.
Every site tested had at least some measurable level of PAH contamination, Baldwin said. 62% of the tested sites had PAH levels that exceeded the “threshold effects concentration,” a level above which harm to living organisms could occur. And 41% of the locations exceeded a level “where harm is probable,” Baldwin said.